Tetrachloro-p-benzoquinone Research Articles

Rapid and Visual Detection of Volatile Amines Based on Their Gas-Solid Reaction with Tetrachloro-p-Benzoquinone.

The detection of volatile amines is necessary due to the serious toxicity hazards they pose to human skin, respiratory systems, and nervous systems. However, traditional amines detection methods require bulky equipment, high costs, and complex measurements. Herein, we report a new simple, rapid, convenient, and visual method for the detection of volatile amines based on the gas-solid reactions of tetrachloro-p-benzoquinone (TCBQ) and volatile amines. The gas-solid reactions of TCBQ with a variety of volatile amines showed a visually distinct color in a time-dependent manner. Moreover, TCBQ can be easily fabricated into simple and flexible rapid test strips for detecting and distinguishing n-propylamine from other volatile amines, including ethylamine, n-butyamine, n-pentamine, n-butyamine and dimethylamine, in less than 3 s without any equipment assistance.

Preparation of a novel poly-(di-ionic liquid)/BDD-modified electrode for the detection of tetrachloro-p-benzoquinone

During the COVID-19 pandemic, the release of toxic disinfection by-products (DBPs) has increased due to the intensive, large-scale use of disinfectants. Halogenated benzoquinones (HBQs) are among the most toxic DBPs, but there is no rapid, convenient, and economical detection method. In this study, a novel PDIL/BDD-modified electrode was prepared in a mixed solvent of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) by electrochemical polymerization with a di-ionic ionic liquid containing alkenyl groups as the monomer. The electrochemical behavior of tetra-chloro-p-benzoquinone (TCBQ) on the modified electrode was studied. By studying the cyclic voltammetry behavior of TCBQ on the PDIL/BDD electrode, it was concluded that the electrode reactions of TCBQ included the reduction of TCBQ to TCBQH2 (C1) and the reduction of bis-quinhydrone imidazole π-π type charge transfer complex to TCBQH2 (C2). By studying the SWV responses of TCBQ in the concentration range of 1–100 ng/L on the PDIL/BDD electrode, it was found that the reduction peak current (Ipa) had a linear relationship with the concentration. The electrochemical SWV technique was used to detect the concentration of trace TCBQ in water and is expected to be used for the detection of other HBQs in drinking water and swimming pool water.

Portable smartphone-assisted RGB-dependent ratiometric sensing platform for the detection of tetrachloro-p-benzoquinone in river samples

Tetrachloro-p-benzoquinone (TC-PBQ) can be harmful to the environment as a pesticide residue, but its analytical detection has been largely neglected. In this work, a smartphone-assisted RGB-dependent TC-PBQ ratiometric sensing platform for rapid recognition is introduced. Here, the red-emitting mercaptopropionic acid-capped CdTe quantum dots (MPA-capped CdTe) as the reaction unit can be quenched by TC-PBQ, while the blue-emitting carbon dots (CDs) as the reference signal remain unchanged. The limit of detection (LOD) of the sensing platform can reach 59 nM in aqueous solution. By constructing an analysis model with the system RBG value, the smartphone-assisted sensor-coated fluorescent test paper can complete the qualitative and quantitative visual detection of TC-PBQ (LOD is 93 nM). The applicability of smartphone-dependent RGB analysis significantly simplifies and speeds up the operation process, which provides a new analytical method for real-time analysis of TC-PBQ in real samples.

Ultraviolet dechlorination of tetrachloro-p-benzoquinone by hydrogen sulfide: Theoretical confirmation of the significance of hydrosulfide radical

In this work, a systematical investigation on the role of hydrogen sulfide (H2S) on the transformation of tetrachloro-p-benzoquinone (TCBQ) under ultraviolet (UV) irradiation (at 253.7 nm) in aqueous solution has been conducted through quantum chemical calculations. Under the UV irradiation, with the forward energy barrier (Ea,f, 11.7 kcal mol−1) much lower than the reverse one (Ea,r, 22.3 kcal mol−1), the first triplet state of TCBQ was kinetically feasible to react with bisulfide anion (HS−) via the Michael addition, and the addition of HS− could promote the release of Cl− and the formation of primary dechlorination product (HS-TriCBQ). During the UV photolysis of the primary dechlorination products (HO-TriCBQ and HS-TriCBQ) in the presence of H2O and H2S, the addition of nucleophile (OH− or HS−) to the ortho-position of the hydroxyl or thiol group might be the most efficient pathway for the dechlorination, and their respective Ea,f were 9.2 kcal mol−1 (for HS−-hydroxyl), 1.1 kcal mol−1 (for OH−-thiol) and 8.9 kcal mol−1 (for HS−-thiol). Moreover, the electron transfer from HS− to the first triplet states could generate hydrosulfide radical for the dechlorination of TCBQ. The findings in the present study may provide some important theoretical foundation for the dehalogenation of TCBQ as well as other halobenzoquinones.

UV photolysis of tetrachloro-p-benzoquinone (TCBQ) in aqueous solution: Mechanistic insight from quantum chemical calculations

In this work, a systematical investigation on the transformation of tetrachloro-p-benzoquinone (TCBQ) under UV irradiation (at 253.7 nm) in aqueous solution has been conducted through quantum chemical calculations. The UV irradiation at 253.7 nm could induce the excitation of TCBQ to its first excited singlet state, followed by the intersystem crossing to its first triplet state. In aqueous solution, the first triplet state of TCBQ was thermodynamically and kinetically feasible to react with H2O via 1,4-addition, where the addition of OH− to the α–β conjugated system was the dominant step. Interestingly, with the addition of hydroxyl to TCBQ, the dechlorination of TCBQ occurred with the formation of the monohydroxylated product of TCBQ (OH-TriCBQ). The UV photolysis pathway of OH-TriCBQ was similar to that of TCBQ, and the 1,4-addition of OH− to the ortho-position of the hydroxyl was the most efficient pathway. The dechlorination by 1,4-addition of OH− was also observed for OH-TriCBQ. With much larger forward energy barriers, the nucleophilic addition of carbonyl by OH− (i.e., 1,2-addition) might be less important for the UV photolysis of TCBQ and OH-TriCBQ. The findings in the present study may help to understand the transformation of TCBQ in aqueous solution.

Preparation of molecularly imprinted polymer based on the magnetic multiwalled carbon nanotubes for selective separation and spectrophotometric determination of melamine in milk samples

A new molecularly imprinted polymers coated on magnetic multiwalled carbon nanotubes (MIPs/MMWCNTs) was synthesized. Synthesized sorbent were characterized by scanning electron microscopy, X-ray diffraction, FT-IR spectroscopy and via adsorption kinetics and adsorption isotherms. The application of this sorbent was investigated in preconcentration and determination with a simple and selective spectrophotometric determination of melamine (MEL) by charge transfer complexation. The method is based on the adsorption of MEL on MIPs/MMWCNTs and subsequent reaction of desorbed MEL with tetrachloro-p-benzoquinone (TCBQ) reagent for final spectrophotometric detection. The effect of experimental parameters affecting separation efficiency and spectrophotometric detection were investigated and optimized. Under optimum conditions, the calibration curve for MEL determination showed a good linearity in the range of 10.0–600.0 ng mL−1 (R2 = 0.999) and the limit of detection (S/N = 3) was estimated to be 3.0 ng mL−1. The intra-day and inter-day precision (RSD%) of MEL were in the range of 2.8–3.9%. This method was successfully applied to determination of MEL in milk and milk powder samples. The good spiked recoveries ranging from 94.6 to 102.3% were obtained.

Understanding charge transfer stacking mode in cocrystals involving Tetrachloro‐p‐benzoquinone via experimental (SXRD, DSC‐TGA, DRS) studies and hirshfeld surfaces analysis

Three binary charge‐transfer cocrystals (Ι, ΙΙ, ΙΙΙ) were obtained by solvent evaporation method, involving 1‐acetyl‐3‐phenyl‐5‐(1‐pyrenyl)‐pyrazoline(APPP), 1‐(5‐(anthracen‐9‐yl)‐3‐(4‐methoxyphen‐yl)‐4,5‐dihydropyrazol‐1‐yl)ethanone (AMPE) and 1‐phenyl‐3‐(pyren‐1‐yl)prop‐2‐en‐1‐one (PPPO) as electron donor (D), Tetrachloro‐p‐benzoquinone (TCQ) as electron acceptor (A), respectively. Single crystal X‐ray diffraction, solid‐state absorption and thermal behaviours were exploited to investigate their structures. For the different types of donors, crystal structure analysis revealed that cocrystal Ι and ΙΙΙ exhibit face‐to‐face mixed‐stacking mode forming DADDAD chains between pyrene moiety and TCQ while cocrystal ΙΙ adopts separated‐stacking mode for AMPE and TCQ molecules. Moreover, Hirshfeld surfaces analysis was utilized to investigate the intermolecular interactions in these cocrystals. The different charge‐transfer stacking modes between donor and acceptor molecules in these crystals can be affected by the design of electron donor.

The acute exposure of tetrachloro-p-benzoquinone (a.k.a. chloranil) triggers inflammation and neurological dysfunction via Toll-like receptor 4 signaling: The protective role of melatonin preconditioning.

This study is aimed to investigate the inflammation and neurological dysfunction induced by tetrachloro-p-benzoquinone (TCBQ) through Toll-like receptor 4 (TLR4) signaling. We also investigated the protective role of melatonin as an antioxidant and anti-inflammatory agent. In vitro model was established by rat pheochromocytoma PC12 cells, meanwhile, TLR4 wild-type (C57BL/6) and knockout mice (C57BL/10ScNJ TLR4-/-) were used as in vivo model. In vitro study showed TCBQ exposure enhanced the expression of TLR4, myeloid differentiation factor 88 (MyD88) at both transcriptional and post-transcriptional levels. By contrast, melatonin decreased TLR4 and MyD88 expressions. Moreover, our result indicated that melatonin disrupted the formation of TLR4/MyD88/MD2/CD14 complex. In addition, melatonin terminated TCBQ-mediated phosphorylation of c-Jun N-terminal kinase (JNK), p38, and extracellular regulated protein kinase (ERK) signaling and hampered its downstream pro-inflammatory cytokine releases. In vivo result also indicated TLR4 deficiency partially protected against TCBQ-induced morphological and neuropathological changes in mice brain, suggested the role of TLR4. In conclusion, melatonin modulates TCBQ-mediated inflammatory genes through TLR4/MyD88-dependent signaling pathway. Our current study, to the best of our knowledge, is the first time show melatonin not only disrupt the binding of TLR4 and MyD88, but also restricted the formation of TLR4/MD2/CD14 complex, suggesting that melatonin supplementary may represent a valuable therapeutic strategy for inflammatory neurological dysfunction.

Synthesis and Electrochemical Performance of a Benzoquinone-Based Polymer Anode for Aqueous Lithium-Ion Batteries

Using the tetrachloro-p-benzoquinone (TCQ) monomer, poly(benzoquinonyl sulfide) (PBQS) was synthesized by a simple polycondensation reaction. The influence of the molar ratio of S to Na2S on the electrochemical performance of a PBQS anode was assessed by changing the amount of S added. The results showed that the electrochemical performance of PBQS strongly depended on the molar ratio of S to Na2S. When the molar ratio of S to Na2S was 0.4, two Cl were replaced by S, and PBQS with a stable structure was obtained. The discharge capacity of PBQS exceeded 140 mAh∙g -1 . At the same time, PBQS displayed satisfactory rate capability and excellent cyclability. Conversely, when the molar ratio of S to Na2S was decreased to 0.25, Cl was not substituted completely and the polymerization degree was low. Upon increasing the molar ratio of S to Na2S to 0.7, an unstable S―S bond may form in the polymer. The above two factors degraded the electrode performance of these materials.

Tetrachloro-p-benzoquinone induces hepatic oxidative damage and inflammatory response, but not apoptosis in mouse: The prevention of curcumin

This study investigated the protective effects of curcumin on tetrachloro-p-benzoquinone (TCBQ)-induced hepatotoxicity in mice. TCBQ-treatment causes significant liver injury (the elevation of serum AST and ALT activities, histopathological changes in liver section including centrilobular necrosis and inflammatory cells), oxidative stress (the elevation of TBAR level and the inhibition of SOD and catalase activities) and inflammation (up-regulation of iNOS, COX-2, IL-1β, IL-6, TNF-α and NF-κB). However, these changes were alleviated upon pretreatment with curcumin. Interestingly, TCBQ has no effect on caspase family genes or B-cell lymphoma 2 (Bcl-2)/Bcl-2 associated X (Bax) protein expressions, which implied that TCBQ-induced hepatotoxicity is independent of apoptosis. Moreover, curcumin was shown to induce phase II detoxifying/antioxidant enzymes HO-1 and NQO1 through the activation of nuclear factor erythroid-derived 2-like 2 (Nrf2). In summary, the protective mechanisms of curcumin against TCBQ-induced hepatoxicity may be related to the attenuation of oxidative stress, along with the inhibition of inflammatory response via the activation of Nrf2 signaling.

Insights into the Mechanism of the Reaction between Tetrachloro‐p‐Benzoquinone and Hydrogen Peroxide and their Implications in the Catalytic Role of Water Molecules in Producing the Hydroxyl Radial

Detailed mechanisms for the formation of hydroxyl or alkoxyl radicals in the reactions between tetrachloro-p-benzoquinone (TCBQ) and organic hydroperoxides are crucial for better understanding the potential carcinogenicity of polyhalogenated quinones. Herein, the mechanism of the reaction between TCBQ and H2O2 has been systematically investigated at the B3LYP/6-311++G** level of theory in the presence of different numbers of water molecules. We report that the whole reaction can easily take place with the assistance of explicit water molecules. Namely, an initial intermediate is formed first. After that, a nucleophilic attack of H2O2 onto TCBQ occurs, which results in the formation of a second intermediate that contains an OOH group. Subsequently, this second intermediate decomposes homolytically through cleavage of the O-O bond to produce a hydroxyl radical. Energy analyses suggest that the nucleophilic attack is the rate-determining step in the whole reaction. The participation of explicit water molecules promotes the reaction significantly, which can be used to explain the experimental phenomena. In addition, the effects of F, Br, and CH3 substituents on this reaction have also been studied.

A DFT study on the electron affinity of tetrachloro-p-benzoquinone: Toward to understanding its electron-accepting ability in solution

Electron affinity (EA) of tetrachloro-p-benzoquinone (TCBQ) has been calculated theoretically without and with water molecules in combination with the polarizable continuum model. It was found that bulk solution and explicit water molecules have an insignificant effect on the geometry of TCBQ. On the other hand, the opposite phenomena are true for the geometry upon capturing an electron. Correspondingly, the vertical and adiabatic EAs of TCBQ have been increased by about 0.2–1.7eV. Moreover, all the EAs and vertical detachment energies are positive and they increase along with the increasing of the dielectric constant of the bulk solvent, confirming that TCBQ is a good electron acceptor in various environmental media.

Theoretical studies on the interaction mechanisms between tetrachloro-p-benzoquinone and hydrogen peroxide

A detailed knowledge of the initial complexes is crucial for the better understanding of the reaction mechanisms between tetrachloro-p-benzoquinone (TCBQ) and hydrogen peroxide (H2O2). In the present study, the interaction modes and interaction mechanisms between TCBQ and H2O2 in the absence and presence of one, two, and three water molecules have been systematically investigated employing the B3LYP/6-311++G** level of theory in combination with the atoms in molecules theory and natural bond orbital (NBO) method. It was found that the introduction of water molecules can influence the original interaction modes between TCBQ and H2O2 through the formation of the intermolecular H-bonds. The interaction energies between TCBQ and H2O2 range from −0.37 to −2.75 kcal/mol for four stable complexes, which are smaller than that of the interaction between H2O2 and water molecule. Further energy decomposition analyses suggest that the coupling interactions between TCBQ and H2O2 are predominated by the electrostatic interactions regardless of the presence or absence of water molecules. In addition, the significant heat released from the interaction process in the presence of water molecules is expected to be favorable for the following reactions involving the production of the hydroxyl radical.

Charge–transfer interaction between melamine and quinones: Towards voltammetric determination of melamine

This communication describes a new voltammetric method for the determination of melamine based on the charge–transfer interaction between quinones and melamine. Three types of quinones, i.e., tetrachloro-p-benzoquinone (TCBQ), benzoquinone (BQ), and vitamin K1 (VK1) were employed in this study. The charge–transfer interaction activity of quinones with melamine was found to depend on the structure of quinones, of which TCBQ with four electron-withdrawing chloro groups exhibits the highest interaction activity with melamine. Such a property was further employed for the voltammetric determination of melamine based on the decrease in the redox peak currents of TCBQ/TCBQ− caused by the pre-consumption of TCBQ with melamine. Under the conditions employed in this study, the decrease in the peak current of TCBQ was linear with the concentration of melamine within a concentration range from 10μM to 1.0mM.

Kinetic modeling of ring byproducts during ozonation of pentachlorophenol in water

Pentachlorophenol (PCP) is a highly toxic material. It is hydrophobic and is recalcitrant to biological degradation. Improper use of PCP has caused serious soil and groundwater contamination problems worldwide, and posed threat to water reclamation processes. The objective of this study was to understand the effects of ozonation on the distributions of ring intermediates during the initial stage of oxidation reactions. Experiments were designed and conducted in a homogeneous condition. Molar ratios of ozone to PCP were controlled in the range from 0.05 to 1.3 at pH 6 to examine dosage effects. Three major ring intermediates quantified were tetrachloro- p-hydroquinone (TCHQ), tetrachloro- p-benzoquinone (TCBQ), and tetrachlorocatechol (TCCA). Transient distributions of these three compounds, together with chloride ions, were monitored. A degradation pathway was proposed and a set of kinetic equations was written accordingly. Rate constants in the kinetic model were obtained by optimizing against experimental data. Ozone dosage was found to be a factor controlling byproducts distributions. Finally, the dynamic sensitivities of rate constants were evaluated for each compound to understand their specific behaviors.

Voltammetric determination of water with inner potential reference and variable linear range based on structure- and redox-controllable hydrogen-bonding interaction between water and quinones

This communication describes a new voltammetric method for the determination of water in nonaqueous solvent by taking advantage of the structure- and redox-controllable hydrogen-bonding interaction between quinone species and water. Three kinds of quinones, i.e., tetrachloro-p-benzoquinone (TCBQ), benzoquinone (BQ), and tetramethyl-p-benzoquinone (TMBQ), are employed in this study in terms of their different structures and thereby different basicities and hydrogen-bonding interaction activities with water. The hydrogen-bonding interaction activities of the quinone species with water actually depend on the structures and the species of quinones, where the interaction activity between quinone dianion and water remains remarkably greater than that between quinone monoanion and water. The former interaction activity eventually leads to the positive shift of the half-wave potential of quinone monoanion/dianion couple, which can be essentially used for the voltammetric determination of water. The structure- and redox-controllable hydrogen-bonding interaction activities of quinones and water substantially make it possible to determine trace amount of water in the nonaqueous solution with inner reference potential and variable dynamic linear range.

Inhibition of jack bean urease by tetrachloro-o-benzoquinone and tetrachloro-p-benzoquinone

Tetrachloro-o-benzoquinone (TCoBQ) and tetrachloro-p-benzoquinone (TCpBQ) were studied as inhibitors of jack bean urease in 20 mM phosphate buffer, pH 7.0, 1 mM EDTA, 25°C. The mechanisms of inhibition were evaluated by analysis of the progress curves obtained with two procedures: the reaction initiated by addition of the enzyme and the reaction initiated by addition of the substrate after preincubation of the enzyme with the inhibitor. The obtained results were characteristic of slow-binding inhibition. The effects of different inhibitor concentrations on the initial and steady-state velocities obeyed the relationships of two-step enzyme-inhibitor interaction, qualified as mechanism B. It was found that TCoBQ and TCpBQ are strong urease inhibitors. TCpBQ is more effective than TCoBQ with the overall inhibition constant of Ki* = 4.5 × 10− 7 mM. The respective inhibition constant of TCoBQ was equal to: Ki* = 2.4 × 10− 6 mM. The protective experiment proved that the urease active site is involved in the tetrachlorobenzoquinone inhibition process. High effectiveness of thiol protectors against inhibition by TCoBQ and TCpBQ indicates the strategic role of the active site sulfhydryl group in the blocking process. The stability of the complexes: urease-TCoBQ and urease-TCpBQ was tested in two ways: by dilution or addition of dithiothreitol. No recovery of urease activity bound in the urease-inhibitor complexes proves that the complexes are stable and strong.

A study of reaction between quinones and thiourea: determination of thiourea in orange juice

The study of the reaction between several quinones and thiourea and the determination of a method for determination of thiourea in orange juice were done. After reaction with thiourea (pH 3.0), the UV-Vis spectra showed new bands only for p-benzoquinone (PBQ) (290 nm, 410 nm), 2,5-dichloro- p-benzoquinone (2,5-DC-PBQ) (330 nm, 420 nm) and tetrachloro- p-benzoquinone (TC-PBQ) (255 nm, 320 nm). The results of FT-IR of the reaction of PBQ and 2,5-DC-PBQ/thiourea showed a substitution of the sulfhydryl group on the ring of quinone. The best concentrations of 2,5-DC-PBQ and PBQ, for determination of thiourea, were 5.0 and 10.0 m m, respectively. The products of reaction 2,5-DC-PBQ and PBQ/thiourea were stable in the period of 2 h and 20–120 min after the heating, respectively. The assay of thiourea using 2,5-DC-PBQ was susceptible to interference by iron (III), copper (II) and ascorbic acid. The detection limit for thiourea with PBQ was 0.90 μg/mL. Using filtration method, the recoveries of thiourea with PBQ from the samples were 100%.

Production of hydroxyl radicals by electrochemically assisted Fenton's reagent: Application to the mineralization of an organic micropollutant, pentachlorophenol

Hydroxyl radicals are very powerful oxidizing agents. They are involved in hydroxylation reactions, in biological and atmospheric phenomena. A recent application of these radicals is their use in decontamination of water polluted by toxic organic substances like pesticides. Chemically, these radicals are produced by the use of a mixture of (H 2O 2+Fe 2+), the so called Fenton's reagent. In this work Fenton's reagent is generated by electrochemistry in a catalytic way. The reaction of the hydroxyl radicals with pentachlorophenol (PCP) was studied. These radicals generated in situ in aqueous solution react with PCP and thus lead to its degradation. The evolution of the composition of the solution was followed by chromatographic analysis, COD analysis and the measurement of the total organic carbon (TOC) of the studied aqueous solution. Tetrachloro- o-benzoquinone and tetrachloro- p-benzoquinone (TCBQ) are the only aromatic intermediates identified. They result from the oxidation of the corresponding tetrachlorohydroquinones (TCHQ). Just like PCP, the TCBQs are degraded and disappear in their turn. The mineralization of the initial toxic substrate is confirmed on the one hand, by the regular decrease in quantity of the total organic carbon of the solution (TOC analysis) and on the other hand, by the quantitative release of chloride ions according to the electrical charge passed during electrolysis. The degradation of PCP appears relatively slow compared to that of the other organic pollutants studied by the electro-Fenton process and also to the degradation of other less substituted chlorophenols. The kinetic rate of the appearance of chloride ions is slower than that in the degradation of PCP. This phenomenon highlights the formation of chlorated aliphatic intermediates.

The radicals formed by photoinduced electron transfer from hypocrellins to electron acceptors

The photoinduced electron transfer from excited singlet and triplet states of hypocrellins to three electron acceptors, namely, methyl viologen chloride (MV), tetrachloro-p-benzoquinone (TCQ) and 2,3-dichloro-5,6-dicyan-p-benzoquinone (DDQ), has been investigated by fluorescence and time-resolved transient absorption spectra. In acetonitrile solution, DDQ and TCQ quenched the fluorescence and T-T absorption of hypocrellins (HA and HB) efficiently, while neither fluorescence nor T-T absorption of them could be quenched by MV. The quenching resulted from the electron transfer between excited hypocrellins and the electron acceptors was controlled by diffusion. The rate constants of electron transfer from excited singlet and triplet of HA to DDQ are 9.20×1010 dm3 mol−1 s−1 and 1.28×109 dm3 mol−1 s−1, respectively. The transient absorption spectra of the formed radical cations of hypocrellins are reported.